This paper proposes a novel standing assistance robot, which considers the posture tolerance of its user. In previous studies, conventional assistive robots did not require patients to use their own physical strength to stand, which leads to decreased strength in the elderly. Therefore, an assistive robot that allows patients to maximally use the physical strength they possess is required. To realize this objective, it is important that a robot assists patients according to their body movement and by their intentions. However, in previous studies, general assistive robots helped patients by using a xed motion reference path- way in spite of their original intention, and as a result, these robots failed to use the physical strength of the patients. Therefore, we propose a novel standing assistance robot, which allows its user to move their body within a prescribed degree of posture tolerance during the process of moving from a sitting to a standing position. Our key ndings cover two fundamental research topics. One is the investigation into posture tolerance during a standing motion. The other topic is a novel assistance control algorithm that considers the investigated posture tolerance by combining position control and force control. A prototype assistive robot, based on the proposed idea was fabricated to help patients stand up safely using the maximum of their remaining physical strength.